Polyester coating compositions containing polymers derived from cyclic carbonates

ABSTRACT

A coating composition is provided that includes (a) a polyester polymer derived by esterifying an aryloxy ether polyol (e.g., an aryloxy ether diol) derived from reaction between a polyhydric phenol or a polyphenol and a non-hydroxyl functional cyclic carbonate, or from reaction between a monophenol and a hydroxyl functional cyclic carbonate; (b) a crosslinker and (c) an optional catalyst.

TECHNICAL FIELD

This invention relates to polyesters, polyester coating compositions andarticles coated with such compositions.

BACKGROUND

The application of coatings to metals to retard or inhibit corrosion iswell established, especially for metal food and beverage cans and othercontainers. Coatings are typically applied to the container interior toprevent the contents from contacting the metal of the container. Contactbetween the metal and the packaged product can lead to corrosion of themetal container, which can contaminate the packaged product. This isparticularly true when the product is chemically aggressive. Protectivecoatings are also applied to the interior of food and beveragecontainers to prevent corrosion in the container headspace between theproduct fill line and the container lid, and is of particular importancefor high-salt-content food products.

Packaging coatings preferably are capable of high-speed application to asubstrate and following hardening preferably meet a variety ofrequirements for this demanding end use. For example, the coating shouldbe safe for food contact; not adversely affect the taste of the packagedfood or beverage product; have excellent adhesion to the substrate;resist staining and other coating defects such as “popping,” “blushing”or “blistering”; and resist degradation over long periods of time, evenwhen exposed to harsh environments. In addition, the coating desirablymaintains film integrity during container fabrication, withstands thevarious processing conditions that the container may be subjected toduring product packaging, and withstands normal usage of the container(e.g., the coating is capable of maintaining its integrity when the canis dropped from a typical height).

A variety of coating compositions, including polyvinyl-chloride-basedcoatings, have been used to form interior protective can coatings.However, the recycling of materials containing polyvinyl chloride orrelated halide-containing vinyl polymers can be problematic.

Bisphenol A and bisphenol F monomers have been used to prepare polymershaving a variety of properties useful for packaging. For example,bisphenol A or bisphenol F may be reacted with phosgene to providepolycarbonates that may be used to form packaging containers, and may bereacted with epichlorohydrin to provide packaging coatings. There is adesire to reduce or eliminate the use of certain bisphenol A-based andbisphenol F-based compounds in containers and coatings, and especiallythose involving contact with foods or beverages. There is also a desireto reduce or eliminate certain epoxy compounds commonly used toformulate food-contact coating compositions.

To address the aforementioned shortcomings, the packaging coatingsindustry has sought coatings based on alternative binder systems such aspolyester resin systems. It has been problematic, however, to formulatepolyester-based coatings that exhibit the required balance of coatingcharacteristics (e.g., flexibility, adhesion, corrosion resistance,stability, resistance to crazing, etc.). For example, there has been atradeoff between corrosion resistance and fabrication properties forsuch coatings. Polyester-based coatings suitable for food contact thathave exhibited both good fabrication properties and an absence ofcrazing have also tended to be too soft and to have unsuitable corrosionresistance. Conversely, polyester-based coatings suitable for foodcontact that have exhibited good corrosion resistance have typicallyexhibited poor flexibility and unsuitable crazing when fabricated.

From the foregoing, it will be appreciated that what remains needed inthe art are improved coating compositions for use in packaging coatings.

SUMMARY

In one aspect, the present invention provides a coating compositioncomprising:

-   -   (a) a polyester polymer derived by esterifying an aryloxy ether        polyol (e.g., an aryloxy ether diol) derived from reaction        between:        -   (i) a polyhydric phenol or a polyphenol and a non-hydroxyl            functional cyclic carbonate, or        -   (ii) a monophenol and a hydroxyl functional cyclic            carbonate;    -   (b) a crosslinker and    -   (c) an optional catalyst.

The aryloxy ether polyol may be esterified by reacting it with a diacidor acid anhydride, or by a transesterification reaction with an esterdifferent from the polyester polymer. In one embodiment, the polyesterpolymer contains additional aromatic rings (e.g., backbone, pendant orterminal aromatic rings) derived from the diacid, acid anhydride or thedifferent ester.

In one embodiment, the polyhydric phenol is a non-hindered diphenol(e.g., a nonsubstituted diphenol) having low estrogenicity. In anotherembodiment, the polyphenol is a hindered bisphenol. In yet anotherembodiment, the monophenol is an alkenyl-substituted monophenol such ascardanol.

In one embodiment, the non-hydroxyl-functional cyclic carbonate isethylene carbonate, propylene carbonate or butylene carbonate. Inanother embodiment, the hydroxyl-functional cyclic carbonate isglycerine carbonate.

In another aspect, the invention provides a method for making a polymeror a coating composition. The method includes (a) preparing an aryloxyether polyol by reacting (i) a polyhydric phenol or a polyphenol and anon-hydroxyl functional cyclic carbonate, or (ii) a monophenol and ahydroxyl functional cyclic carbonate, and (b) preparing a polyesterpolymer by esterifying the aryloxy ether polyol. The method may furtherinclude (c) combining the polyester polymer with a crosslinker and anoptional catalyst to form a crosslinkable coating composition.

In another aspect, the invention provides an article coated on at leastone surface with the above-described coating composition. In certainembodiments, the coated article comprises a food or beverage can, or aportion thereof, having a body portion (e.g., an interior portion) or anend portion coated with the disclosed coating composition.

In yet another aspect, the invention provides a method for producing acoated article. The method includes providing the above-describedcoating composition and applying it on a substrate (typically a metalsubstrate and in some embodiments a planar metal substrate) prior to,during, or after forming the substrate into an article such as food orbeverage can or other container or a portion thereof.

The above summary of the present invention is not intended to describeeach disclosed embodiment or every implementation of the presentinvention. The description that follows more particularly exemplifiesillustrative embodiments. In several places throughout the application,guidance is provided through lists of examples, which examples can beused in various combinations. In each instance, the recited list servesonly as a representative group and should not be interpreted as anexclusive list. Other features, objects, and advantages of the inventionwill be apparent from the description and from the claims.

SELECTED DEFINITIONS

Unless otherwise specified, the following terms as used herein have themeanings provided below.

As used herein, “a,” “an,” “the,” “at least one,” and “one or more” areused interchangeably. Thus, for example, a coating composition thatcomprises “an” additive can be interpreted to mean that the coatingcomposition includes “one or more” additives.

The term “bisphenol” refers to a polyphenol having two phenylene groupsthat each include a six-carbon ring and a hydroxyl group attached to acarbon atom of the ring, wherein the rings of the two phenylene groupsdo not share any atoms in common.

The term “comprises” and variations thereof do not have a limitingmeaning where these terms appear in the description and claims. Thedisclosed compositions may in any event comprise, consist essentially ofor consist of the recited elements.

The term “crosslinker” refers to a molecule capable of forming acovalent linkage between copolymers (e.g., between polymers) or betweentwo different regions of the same copolymer.

The term “dihydric phenol” refers to a diol having two hydroxyl groupseach attached to a carbon atom of a six-carbon ring.

The term “diphenol” may as the context requires refer to a bisphenol orto a dihydric phenol.

The term “easy open end” refers to a can end (typically an end of a foodor beverage container) that includes (i) a frangible opening portion(which for some beverage can ends functions as a drinking spout) and(ii) a riveted portion for attaching a pull tab thereto for purposes ofopening the frangible opening portion to access the product housedwithin a can or container.

The term “epoxy-free”, when used herein in the context of a polymer,refers to a polymer that does not include any “epoxy backbone segments”(viz., segments formed from reaction of an epoxy group and a groupreactive with an epoxy group). By way of example, a polymer made fromingredients including an epoxy resin would not be considered epoxy-free.Similarly, a polymer having backbone segments that are the reactionproduct of a bisphenol (e.g., bisphenol A, bisphenol F, bisphenol S,4,4′dihydroxy bisphenol, etc.) and a halohydrin (e.g., epichlorohydrin)would not be considered epoxy-free. However, a vinyl polymer formed fromvinyl monomers or oligomers that include a pendant epoxy moiety (e.g.,glycidyl methacrylate) would be considered epoxy-free because the vinylpolymer would be free of epoxy backbone segments.

The terms “esterified”, “esterified” and “esterification” include esterforming reactions (e.g., reaction of a polyol with an acid or acidanhydride) and ester interchange reactions (e.g., transesterification)

The terms “estrogenicity”, “estrogenic activity” or “estrogenic agonistactivity” refer to the ability of a compound to mimic hormone-likeactivity through interaction with an endogenous estrogen receptor,typically an endogenous human estrogen receptor.

The term “food-contact surface” refers to a surface of an article (e.g.,a food or beverage container) that is in contact with, or suitable forcontact with, a food or beverage product. When used in the context of acoating composition applied on a food-contact surface of a packagingarticle (e.g., a food or beverage container), the term refers to theunderlying substrate (typically associated with an interior surface ofthe packaging article) on which the coating composition is applied, anddoes not imply that the underlying portion of the substrate will be incontact with a food or beverage product.

The term “mobile” when used in respect to a compound in a cured coatingmeans that the compound can be extracted from the cured coating when acoating (typically ˜1 milligram per square centimeter (mg/cm²) or 6.5mg/in² thick) is exposed to a test medium for some defined set ofconditions, depending on the end use. An example of these testingconditions is exposure of the cured coating to HPLC-grade acetonitrilefor 24 hours at 25° C.

The term “monophenol” refers to a compound having one hydroxyl groupattached to a carbon atom of a six-carbon ring.

The term “on”, when used in the context of a coating applied on asurface or substrate, includes both coatings applied directly orindirectly to the surface or substrate. Thus, for example, a coatingapplied to a primer layer overlying a substrate constitutes a coatingapplied on the substrate.

The term “organic group” means a hydrocarbon group (with optionalelements other than carbon and hydrogen, such as oxygen, nitrogen,sulfur, and silicon) that may be further classified as an aliphaticgroup, cyclic group (e.g., aromatic and cycloaliphatic groups), orcombination of aliphatic and cyclic groups (e.g., alkaryl, and aralkylgroups). The term “aliphatic group” means a saturated or unsaturatedlinear or branched hydrocarbon group. This term is used to encompassalkyl, alkylene, alkenyl, and alkynyl groups, for example. The term“alkyl group” means a saturated monovalent linear or branchedhydrocarbon group having for example 1 to 12, 1 to 10 or 1 to 8 carbonatoms (e.g., an n-propyl or isopropyl group), and the term “alkylenegroup” means a saturated divalent linear or branched hydrocarbon grouphaving for example 1 to 12, 1 to 10 or 1 to 8 carbon atoms (e.g., apropylene group). The term “alkenyl group” means an unsaturated, linearor branched hydrocarbon group with one or more carbon-carbon doublebonds (e.g., a vinyl group), and the term “alkynyl group” means anunsaturated, linear or branched hydrocarbon group with one or morecarbon-carbon triple bonds (e.g., an ethynyl group). The term “cyclicgroup” means a closed ring hydrocarbon group that is classified as analicyclic group or an aromatic group, both of which can includeheteroatoms. The term “alicyclic group” means a cyclic hydrocarbon grouphaving properties resembling those of aliphatic groups. A group that maybe the same as or different from other groups may be referred to asbeing “independently” something. Substitution on the organic groups ofcompounds of the present invention is contemplated. The terms “group”and “moiety” may be used to differentiate between chemical species thatallow for substitution or that may be substituted and those that do notallow or may not be so substituted. The term “group” is intended to be arecitation of both the particular moiety, as well as a recitation of thebroader class of substituted and unsubstituted structures that includethe moiety. Thus, when the term “group” is used to describe a chemicalsubstituent, the described substituent includes the unsubstituted groupand that group with O, N, Si, or S atoms, for example, in the chain (asin an alkoxy group) as well as carbonyl groups or other conventionalsubstitution. Where the term “moiety” is used to describe a chemicalcompound or substituent, only an unsubstituted chemical material isintended to be included. For example, the phrase “alkyl group” isintended to include not only pure open chain saturated hydrocarbon alkylsubstituents, such as methyl, ethyl, isopropyl, t-butyl, heptyl,dodecyl, octadecyl, amyl, 2-ethylhexyl, and the like, but also alkylsubstituents bearing further substituents known in the art, such ashydroxy, alkoxy, alkylsulfonyl, halogen atoms, cyano, nitro, amino,carboxyl, etc. Thus, “alkyl, group” includes ether groups, haloalkyls,nitroalkyls, carboxyalkyls, hydroxyalkyls, sulfoalkyls, etc. On theother hand, the phrase “alkyl moiety” is limited to the inclusion ofonly pure open chain saturated hydrocarbon alkyl substituents, such asmethyl, ethyl, isopropyl, t-butyl, heptyl, dodecyl, octadecyl, amyl,2-ethylhexyl, and the like.

Unless otherwise indicated, the term “polymer” includes bothhomopolymers and copolymers (viz., polymers of two or more differentmonomers).

The term “polyphenol” refers to a polyhydric material having two or morephenylene groups that each include a six-carbon ring and a hydroxylgroup attached to a carbon atom of the ring, wherein the rings of thephenylene groups do not share any atoms in common.

The terms “preferred” and “preferably” refer to embodiments of theinvention that may afford certain benefits, under certain circumstances.However, other embodiments may also be preferred, under the same orother circumstances. Furthermore, the recitation of one or morepreferred embodiments does not imply that other embodiments are notuseful, and is not intended to exclude other embodiments from the scopeof the invention.

The term “substantially free” when used with respect to a coatingcomposition that may contain a particular mobile compound means that thecoating composition contains less than 1,000 parts per million (ppm) ofthe recited mobile compound. The term “essentially free” when used withrespect to a coating composition that may contain a particular mobilecompound means that the coating composition contains less than 100 partsper million (ppm) of the recited mobile compound. The term “essentiallycompletely free” when used with respect to a coating composition thatmay contain a particular mobile compound means that the coatingcomposition contains less than 5 parts per million (ppm) of the recitedmobile compound. The term “completely free” when used with respect to acoating composition that may contain a particular mobile compound meansthat the coating composition contains less than 20 parts per billion(ppb) of the recited mobile compound. If the aforementioned phrases areused without the term “mobile” (e.g., “substantially free of BPAcompound”) then the compositions of the present invention contain lessthan the aforementioned amount of the compound whether the compound ismobile in the coating or bound to a constituent of the coating.

The term “unsaturation” when used in the context of a compound refers toa compound that includes at least one non-aromatic carbon-carbon doubleor triple bond.

The term “vinyl organosol” means a dispersion of vinyl chloride polymers(preferably high-molecular-weight vinyl chloride polymers) in a liquidcarrier.

The recitations herein of numerical ranges by endpoints include allnumbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, 5, etc.). Furthermore, disclosure of a range includesdisclosure of all subranges included within the broader range (e.g., 1to 5 discloses 1 to 4, 1.5 to 4.5, 1 to 2, etc.).

DETAILED DESCRIPTION

Conventional food-contact, high performance packaging coatings havetypically been based on epoxy resins. The presence in such resins ofsegments derived from diphenols may contribute to their highperformance. It would be desirable to prepare high performance packagingcoatings from polyesters containing segments derived from diphenols.However, introducing such segments into a polyester backbone isdifficult. The presently disclosed coating compositions includepolyester polymers having segments derived from diphenols or monophenolsin the polyester backbone. The polymers may be made by converting adiphenol or monophenol into an aryloxy ether polyol (preferably anaryloxy ether diol or aryloxy polyether diol) via a ring-openingreaction with a cyclic carbonate (for example, a cyclic alkylenecarbonate). The resulting aryloxy ether polyol may be esterified bypost-reaction with a diacid or acid anhydride, or esterified via atransesterification reaction with an ester different from the finalpolyester. The final polyester may for example contain additionalaromatic rings (e.g., backbone, pendant or terminal aromatic rings)derived from the diacid, acid anhydride or the different ester.Preferred cured coatings of the invention exhibit a desirable balance oftwo or more coating properties, for example a desirable balance of twoor more of adhesion, corrosion resistance, flexibility and ease offabrication.

In one embodiment, a dihydric phenol of Formula I is reacted with anon-hydroxyl-functional cyclic carbonate of Formula II to prepare anaryloxy ether diol of Formula III:

wherein:

-   -   each R¹ may be the same or different and independently is a        monovalent atom (for example, hydrogen or a heteroatom such as a        halogen, S or N) or a monovalent organic group (for example, an        aliphatic or cycloaliphatic group that may be linear or        branched, or an aromatic group) and may contain heteroatoms (for        example, O, N or S atoms), with R¹ preferably being hydrogen;    -   R² is hydrogen (in which case the cyclic carbonate of Formula II        is ethylene carbonate) or an organic group (for example, a        methyl or ethyl group, in which case the cyclic carbonate of        Formula II is respectively propylene carbonate or butylene        carbonate)), with R² preferably being hydrogen;    -   x is 0 to about 2 and usually is zero or nearly zero; and    -   y is 1 to about 10 and usually is 1 to about 5.

When R² in Formula II is an alkyl group rather than hydrogen, thealiphatic cyclocarbonate carbon atoms in Formula II may have differentreactivities with respect to the phenolate anion derived by removal of aproton from the compound of Formula I, and may result in a mixture ofisomeric reaction products. The phenolate anion may also react with thecarbonyl carbon atom in Formula II to provide further isomeric reactionproducts. A variety of structures may accordingly be formed, includingfor example compounds containing segments of Formulas IV and V shownbelow:

wherein R², x and y are as defined above. The various formed structurestypically will include a terminal primary or secondary alcohol group.

A variety of Formula I dihydric phenols may be employed to make thearyloxy ether polyols of Formula III, including the compounds of FormulaVI shown below:

wherein:

-   -   each R³, if present, is preferably independently an atom or        group preferably having at atomic weight of at least 15 Daltons;    -   w is 0 to 4; and    -   two or more R³ groups can optionally join to form one or more        cyclic groups (e.g., a divalent cyclic group).

Exemplary dihydric phenol compounds of Formula VI include catechol andsubstituted catechols (e.g., 3-methylcatechol, 4-methylcatechol,4-tert-butyl catechol, and the like); hydroquinone and substitutedhydroquinones (e.g., methylhydroquinone, 2,5-dimethylhydroquinone,trimethylhydroquinone, tetramethylhydroquinone, ethylhydroquinone,2,5-diethylhydroquinone, triethylhydroquinone, tetraethylhydroquinone,tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, and the like);resorcinol and substituted resorcinols (e.g., 2-methylresorcinol,4-methyl resorcinol, 2,5-dimethylresorcinol, 4-ethylresorcinol,4-butylresorcinol, 4,6-di-tert-butylresorcinol,2,4,6-tri-tert-butylresorcinol, and the like); and variants and mixturesthereof.

In place of or as part of a mixture with the compounds of Formula I, avariety of bisphenol compounds may instead or also be reacted with anon-hydroxyl-functional cyclic carbonate of Formula II to prepare anaryloxy ether diol of Formula III. Exemplary such bisphenols includethose (for example, the bis-4-hydroxybenzoate of cyclohexanedimethanol)described in U.S. Pat. No. 8,129,495 B2 (Evans et al. '495); thebisphenols disclosed in U.S. Patent Application Publication Nos. US2013/0206756 A1 (Niederst et al. '756) and US 2013/0052381 A1 (Gallucciet al.), and the bisphenols disclosed in International Application No.WO 2013/119686 A1 (Niederst et al. '686), including2,2′-methylenebis(6-tert-butyl-4-methylphenol) which is available asIONOL™ 46 from Raschig GmbH; 4,4′-methylenebis(2,6-di-tert-butylphenol)which is available as IONOL 220 from Raschig GmbH;4,4′-butylidenebis[2-tert-butyl-5-methylphenol] which is available asLOWINOX™ 44B25 from Addivant; spirobiindane bisphenols; and bis-(hydroxyphenyl)-N-phenyl isoindolinone. A preferred class of bisphenols includethe compounds of Formula IA shown below:

wherein:

-   -   H denotes a hydrogen atom, if present;    -   A, if present, is preferably a divalent organic group;    -   R³ is as defined above, wherein each of the phenylene rings        depicted in Formula IA preferably includes at least one R³ group        attached to the phenylene ring at an ortho or meta position        relative to the hydroxyl group and wherein two or more R³ groups        can join with one another or with the A group to form one or        more cyclic groups (e.g., a divalent cyclic group);    -   m is 0 or 1, with the proviso that if m is 0, the phenylene        rings depicted in Formula IA can optionally join with each other        to form a fused ring system (e.g., a substituted naphthalene        ring), in which case v is 3 (as opposed to 4) and w is 0 to 3        (as opposed to 0 to 4);    -   v is 4; and    -   w is as defined above, and preferably is 1 to 4, and more        preferably is 2 to 4.

Exemplary compounds of Formula IA include the hindered bisphenols (forexample, 4,4′-methylenebis(2,6-dimethylphenol, also known as tetramethylbisphenol F or TMBPF) described in U.S. Patent Application PublicationNo. US 2013/0316109 A1 (Niederst et al. '109); and bisphenols (includingsubstituted and nonsubstituted diphenols) having low estrogenicity (forexample, 4,4′-(1,4-phenylenebis(propane-2,2-diyl))diphenol and2,2′methylenebis(phenol)) as also described in Niederst et al. '109.

Exemplary non-hydroxyl-functional cyclic carbonates of Formula II foruse in making the compounds of Formula III include ethylene carbonate,propylene carbonate and butylene carbonate, each of which iscommercially available as a JEFFSOL™ alkylene carbonate from HuntsmanCorporation.

The reaction to make compounds of Formula III preferably employs acatalyst. Suitable catalysts include phosphines, tertiary amines andmaterials such as those described in U.S. Pat. No. 2,967,892 (Smith);U.S. Pat. No. 2,987,555 (Davis); U.S. Pat. No. 4,261,922 (Kern); U.S.Pat. No. 4,310,706 (Strege '706); U.S. Pat. No. 4,310,707 (Strege '707);U.S. Pat. No. 4,310,708 (Strege et al.); 4,341,905 (Strege '905); U.S.Pat. No. 4,348,314 (Lazarus et al.); U.S. Pat. No. 5,059,723 (Dressler)and U.S. Pat. No. 5,998,568 (Nava). A tertiary amine known as “DBN”(1,5-Diazabicyclo[4.3.0]non-5-ene, CAS No. 3001-72-7) is a preferredcatalyst.

To minimize the amount of unreacted Formula I diphenol in the finalproduct, it is desirable to employ an excess, e.g., approximately a 10to 20% molar excess, of the non-hydroxyl-functional cyclic carbonate ofFormula II. The types of and ratio between the Formula I and Formula IIreactants and the reaction conditions will also affect the respectiveamounts of the Formula III bracketed segments bearing the subscripts xand y in the final product. The reaction progress may be monitored usinginfrared spectroscopy to measure the appearance of carbonate groups orby observing the evolution of CO₂ bubbles from the reaction mixture.

In another embodiment, a monophenol of Formula VII is reacted with ahydroxyl-functional cyclic carbonate of Formula VIII to prepare anaryloxy ether polyol of Formula IX:

wherein:

-   -   each R⁴ may be the same or different and independently is a        monovalent atom (for example, hydrogen or a heteroatom such as a        halogen, S or N) or a monovalent organic group (for example, an        aliphatic or cycloaliphatic group that may be linear or        branched, or an aromatic group) which optionally may contain        heteroatoms (for example, O, N or S atoms) or unsaturation, and        with one such R⁴ group preferably being present and the        remaining R⁴ groups preferably being hydrogen;    -   R⁵ is an alkylene group (for example, a methylene group, in        which case the cyclic carbonate of Formula VII is glycerine        carbonate); and    -   x and y are as defined above.

A mixture of products may be obtained, containing products of Formula IXand products in which the bracketed segments in Formula IX bearing thesubscripts x and y are replaced by one or both of the bracketed segmentsof Formulas X and XI shown below:

wherein R⁵, x and y are as defined above.

A variety of Formula VII monophenols may be employed. Exemplary suchmonophenols include alkenyl-substituted phenols such as cardanol, whichis a meta-substituted phenol derived from cashew nut shell liquid. Ageneralized structure for cardanol is shown below as Formula XII:

wherein:

-   -   n corresponds to the number of carbon-carbon double bonds        present in the alkenyl side chain and is typically 0, 1, 2 or 3.

When more than one carbon-carbon double bond is present in themeta-positioned alkenyl chain of Formula XII, the carbon-carbon doublebonds may be conjugated or non-conjugated. Since cardanol is derivedfrom a naturally occurring feedstock, commercial feedstocks of cardanolmay contain variants of the above generalized structure (e.g., compoundshaving a second hydroxyl group at the “open” meta position) and minoramounts of other compounds. It is contemplated that compounds having theabove generalized structure may be reacted on the alkenyl chain withoutaffecting significantly the beneficial reactive properties of thephenolic ring. In addition, the phenolic ring itself may be furthersubstituted, if desired.

Exemplary hydroxyl-functional cyclic carbonates of Formula VIII for usein making the compounds of Formula IX include glycerine carbonate, whichis commercially available as a JEFFSOL™ alkylene carbonate from HuntsmanCorporation.

The reaction to make compounds of Formula IX preferably employs acatalyst. Suitable catalysts include those described above in connectionwith making the compounds of Formula III.

To minimize the amount of unreacted Formula VII monophenol in the finalproduct, it is desirable to employ an excess, e.g., approximately a 20to 30% molar excess, of the hydroxyl-functional cyclic carbonate ofFormula VIII. The ratio between the reactants of Formula VII and FormulaVIII and the reaction conditions will also affect the respective amountsof the bracketed segments in Formula IX bearing the subscripts x and y,and the respective amounts of compounds containing the bracketedsegments of Formula X and XIV, that will be obtained in the finalproduct. The reaction progress may be monitored using infraredspectroscopy to measure the disappearance of carbonate group absorptionbands or by observing the evolution of CO₂ bubbles from the reactionmixture.

The above-described product compounds of Formula III and Formula IX maybe used as is or purified prior to use in a polyester formationreaction. The selected purification method, if used, may depend onfactors including the chosen reaction scheme, yield, byproducts and theform (e.g., solid or liquid) in which the product is obtained. Exemplarypurification methods will be familiar to persons having ordinary skillin the art and include washing with solvent, solvent extraction,flotation, filtration, centrifugation, evaporation, crystallization,recrystallization, fractionation, electrolysis, sublimation, adsorption,distillation and biological methods including fermentation, microbes andenzymes. Preferably the product compounds of Formula III or Formula IXare liquids, the viscosity and crystallization level of which may dependon the reactants employed. A purification method, if required, may bechosen by taking into account the product physical state and itssolubility in various solvents.

The compounds of Formula III and Formula IX may be used to preparepolyester polymers using standard reaction procedures, including afusion process like that described in U.S. Pat. No. 3,109,834 or anazeotropic distillation process like that described in U.S. PatentApplication Publication No. US 2009/0198005 A1. The polyester may beformed by direct esterification or transesterification, with directesterification being preferred. A compound of Formula III or Formula IXtypically is combined with at least one dicarboxylic acid or acidanhydride, and with the optional addition of other di-, tri- orhigher-functional polyols and the optional addition of other di-, tri-or higher-functional polycarboxylic acids. Exemplary di- andhigher-functional polycarboxylic acids and acid anhydrides includemaleic acid, fumaric acid, succinic acid, adipic acid, phthalic acid,tetrahydrophthalic acid, methyltetrahydrophthalic acid,hexahydrophthalic acid, methylhexahydrophthalic acid,endomethylenetetrahydrophthalic acid, azelaic acid, sebacic acid,tetrahydrophthalic acid, isophthalic acid, trimellitic acid,terephthalic acid, naphthalene dicarboxylic acids, cyclohexanedicarboxylic acid, glutaric acid, dimer fatty acids, nadic acid, methylnadic acid, anhydrides of the foregoing (e.g., maleic anhydride, nadicanhydride, etc.) and mixtures thereof. For the sake of brevity, suchcompounds can be referred to collectively as “carboxylic acids.” Ifdesired, adducts of polyacid compounds (e.g., triacids, tetraacids,etc.) and monofunctional compounds may be used. An example of one suchadduct is pyromellitic anhydride pre-reacted with benzyl alcohol. Esterderivatives of the foregoing carboxylic acids (e.g., methyl, ethyl orother alkyl esters) and mixtures thereof may be used fortransesterification reactions.

Di- and higher-functional polyols may also be present during theesterification reaction. Examples of suitable other di- andhigher-functional polyols include ethylene glycol, propylene glycol,1,3-propanediol, 2-methyl-1,3-propanediol,2-butyl-2-ethyl-1,3-propanediol, glycerol, diethylene glycol,dipropylene glycol, triethylene glycol, trimethylolpropane,trimethylolethane, tripropylene glycol, neopentyl glycol,pentaerythritol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol,1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol,2-methyl-2,4-pentanediol, 4-methyl-2,4-pentanediol, 2,2,4-trimethyl1-3-pentanediol, 1,5-pentanediol, 1,6-hexanediol,2,2-dimethyl,1,3-hexanediol, cyclohexanedimethanol, a polyethylene orpolypropylene glycol, isopropylidene bis (p-phenylene-oxypropanol-2),hydroxypivalyl hydroxypivalate and mixtures thereof. If desired, adductsof polyol compounds (e.g., triols, tetraols, etc.) and monofunctionalcompounds may be used. An example of one such adduct isdipentaerythritol pre-reacted with benzoic acid.

The polyester polymer may have any suitable hydroxyl number. Hydroxylnumbers are typically expressed as milligrams of potassium hydroxide(KOH) equivalent to the hydroxyl content of 1 gram of thehydroxyl-containing substance. Methods for determining hydroxyl numbersare well known in the art, and are shown for example in ASTM D 1957-86(Reapproved 2001) entitled “Standard Test Method for Hydroxyl Value ofFatty Oils and Acids”. In some embodiments, the polyester polymer has ahydroxyl number of 0 to about 150, about 10 to about 150, 25 to about100, or about 30 to about 80.

The polyester polymer may have any suitable acid number. Acid numbersare typically expressed as milligrams of KOH required to titrate a 1gram sample to a specified end point. Methods for determining acidnumbers are well known in the art, and are shown for example in ASTM D974-04 entitled “Standard Test Method for Acid and Base Number byColor-Indicator Titration”. In some embodiments (e.g., when thepolyester polymer is intended for use in an organic-solvent basedcoating composition), the polyester polymer has an acid number of lessthan about 20, less than about 10, or less than about 5. In otherembodiments (e.g., when the polyester polymer is intended for use in awater-based coating composition, the acid number may be appreciablyhigher (e.g., greater than 20, greater than 50 or greater than 100).

The molecular weight of the polyester polymer may vary depending upon avariety of factors including the chosen raw materials and the desiredend use. In some embodiments the polyester polymer has a number averagemolecular weight (Mn) of at least about 1,000, at least about 1,500, orat least about 3,000. In some embodiments the polyester polymer has anMn less than about 20,000, less than about 15,000, or less than about10,000.

The polyester polymer may contain a plurality of segments derived from(viz., obtainable by removal of the hydroxyl hydrogen atoms from) thearyloxy ether polyol. In some embodiments the polyester polymer containsat least about 4 wt. %, at least about 8 wt. % or at least about 10 wt.% such segments, based on the aryloxy ether polyol weight compared tothe dry (viz., solvent-free) polyester polymer weight. In someembodiments the polyester polymer contain less than about 50 wt. %, lessthan about 40 wt. % or less than about 35 wt. % such segments, based onthe aryloxy ether polyol weight compared to the dry polyester polymerweight.

The polyester polymer may contain segments derived from long chainlength oils, but desirably is sufficiently free of such oil segments soas to be suitable for use in a packaging coating. In some embodimentsthe polyester polymer is derived from less than 15 wt. % oils having 15or more carbon atoms, based on the oil weight compared to the drypolyester polymer weight.

The polyester polymer may contain aromaticity derived from theabove-mentioned polyhydric phenol, polyphenol, diacid, acid anhydride orester different from the polyester polymer. The amount of aromatic ringcontent may for example be like the aromatic ring content amountspresent in conventional BPA-epoxy-derived packaging coatings, such asDGEBPA packaging coatings derived from the diglycidyl ether of bisphenolA. In some embodiments the disclosed polyester polymer contains at leastabout 5 wt. %, at least about 10 wt. % or at least about 15 wt. %aromatic ring segments, based on the weight of aromatic ring carbonatoms compared to the dry polyester polymer weight. In some embodimentsthe polyester polymer contain less than about 50 wt. %, less than about40 wt. % or less than about 30 wt. % aromatic ring segments, based onthe weight of aromatic ring carbon atoms compared to the dry polyesterpolymer weight.

The polyester polymer may have any suitable glass transition temperature(Tg). In some embodiments the polyester polymer has a Tg of at least 0°C., at least 5° C., or at least 10° C. In embodiments in which thepolyester polymer is intended for use in an internal food or beveragecan coating, it may be desirable that the polyester polymer have a Tg ofat least 30° C., at least 40° C., or at least 50° C. In someembodiments, the polyester polymer has a Tg less than 100° C., less than80° C., or less than 60° C. The aforementioned Tg values are withrespect to the polyester polymer prior to cure of the coatingcomposition.

The disclosed coating compositions may include any suitable amount ofthe polyester polymer to produce the desired result. In someembodiments, the coating compositions include at least about 10, atleast about 15, or at least about 20 wt. % polyester polymer, based onthe total nonvolatile weight of the coating composition. In someembodiments, the coating compositions include less than about 90, lessthan about 85, or less than about 80 wt. % polyester polymer, based onthe total nonvolatile weight of the coating composition.

The polyester polymer may be made water dispersible or water solubleusing a variety of techniques. For example, the polyester polymer may bemodified to contain a suitable amount of salt-containing or salt-forminggroups to facilitate preparation of an aqueous dispersion or solution.Suitable salt-forming groups may include neutralizable groups such asacidic or basic groups. At least a portion of the salt-forming groupsmay be neutralized to form salt groups useful for dispersing thepolyester polymer into an aqueous carrier. Acidic or basic salt-forminggroups may be introduced into the polyester polymer by any suitablemethod. For example, carboxylic acid groups may be introduced into ahydroxyl group-containing polyester polymer via reaction with apolyanhydride such as tetrahydrophthalic anhydride, pyromelliticanhydride, succinic anhydride, trimellitic anhydride (“TMA”) or mixturethereof. In one embodiment, a polyester polymer or oligomer having oneor more pendant and preferably terminal hydroxyl groups is reacted withan anhydride such as TMA to produce a carboxyl-functional polyesterpolymer or oligomer. The conditions of the reaction, including thetemperature, are desirably controlled to avoid gelling. Thecarboxylic-functional polyester polymer or oligomer is neutralized(e.g., using a base such as a tertiary amine) to form salt groups and anaqueous dispersion. In embodiments in which the polyester polymerincludes unsaturation in the polymer backbone or in a pendant group,water dispersibility may be provided by grafting an acid-functionalethylenically unsaturated monomer or an acrylic polymer onto thepolyester to form a partly-grafted polyester-acrylic copolymer.Exemplary polyester polymers containing such unsaturation includecompounds of Formula IX made from an alkenyl-substituted phenol such ascardanol, and polyester polymers made using unsaturated acids or acidanhydrides such as fumaric acid, maleic anhydride or nadic anhydride.All or a suitable number of the acid-functional groups in the resultingpolyester-acrylic copolymer may be neutralized with a base (for example,a tertiary amine) to form salt groups and an aqueous dispersion. Furtherinformation regarding such techniques may be found, for example in U.S.Patent Application Publication No. US 2005/0196629 A1.

The disclosed polyester polymers and coating compositions preferably aresubstantially free, more preferably essentially free, even morepreferably essentially completely free, and optimally completely free ofmobile bisphenol A (BPA) and aromatic glycidyl ether compounds.Exemplary such aromatic glycidyl ether compounds include diglycidylethers of bisphenol (BADGE), diglycidyl ethers of bisphenol F (BFDGE)and epoxy novalacs. In some embodiments, the disclosed polyesterpolymers and coating composition are preferably substantially free, morepreferably essentially free, even more preferably essentially completelyfree, and optimally completely free of bound BPA and aromatic glycidylether compounds including BADGE, BFDGE and epoxy novalacs. The disclosedpolyester polymers and coating compositions preferably are also at leastsubstantially “epoxy-free” and more preferably “epoxy-free.”

A variety of crosslinkers may be used in the disclosed coatingcompositions. Exemplary crosslinkers include phenolic crosslinkers.(e.g., phenoplasts), including novolac- and resole-type resins; aminocrosslinkers (e.g., aminoplasts); blocked isocyanate crosslinkers;materials containing oxirane groups (e.g., oxirane-functional polyesterssuch as glycidol-modified polyesters or oxirane-functional vinylpolymers such as acrylic resins formed using glycidyl methacrylate) andcombinations thereof. Further information regarding glycidol-modifiedpolyesters may be found in U.S. Patent Application Publication No. US2012/0125800 A1. Preferred crosslinkers are at least substantially free,more preferably completely free, of bound BPA and aromatic glycidylethers. Resole phenolic crosslinkers are preferred. The crosslinkerconcentration may vary depending upon the desired result. For example,in some embodiments, the coating composition may contain from about 0.01wt. % to about 40 wt. %, about 0.5 wt. % to about 35 wt. %, or about 3wt. % to about 30 wt. % crosslinker(s) based on the total weight ofnonvolatile materials in the coating composition. In other embodiments,the coating composition may contain at least about 5, at least about 10,or at least about 15 wt. % crosslinker(s) based on the total weight ofnonvolatile materials in the coating composition.

Examples of suitable phenolic crosslinkers include the reaction productsof aldehydes with phenols. Formaldehyde and acetaldehyde are preferredaldehydes. Examples of suitable phenols include phenol, cresol,p-phenyphenol, p-tert-butylphenol, p-tert-amylphenol, cyclopentylphenol,cresylic acid, BPA (not presently preferred), and combinations thereof.Exemplary resole phenolic crosslinkers include DUREZ™ 33160 and 33162(each available from Durez Corporation), BAKELITE™ 6535 and 6470 (eachavailable from Hexion Specialty Chemicals GmbH), PHENODUR™ PR 285 and PR812 (each available from Cytec Surface Specialties), SFC™ 112 and 142(each available from the SI Group) and mixtures thereof.

Amino crosslinker resins are typically the condensation products ofaldehydes (e.g., such as formaldehyde, acetaldehyde, crotonaldehyde, andbenzaldehyde) with amino- or amido-group-containing substances (e.g.,urea, melamine and benzoguanamine). Suitable amino crosslinking resinsinclude, for example, benzoguanamine-formaldehyde-based resins,melamine-formaldehyde-based resins (e.g., hexamethonymethyl melamine),etherified melamine-formaldehyde, urea-formaldehyde-based resins, andmixtures thereof. Condensation products of other amines and amides canalso be employed such as, for example, aldehyde condensates oftriazines, diazines, triazoles, guanadines, guanamines and alkyl- andaryl-substituted melamines. Exemplary such compounds includeN,N′-dimethyl urea, benzourea, dicyandimide, formaguanamine,acetoguanamine, glycoluril, ammelin 2-chloro-4,6-diamino-1,3,5-triazine,6-methyl-2,4-diamino-1,3,5-triazine, 3,5-diaminotriazole,triaminopyrimidine, 2-mercapto-4,6-diaminopyrimidine,3,4,6-tris(ethylamino)-1,3,5-triazine, and the like. While the aldehydeemployed is typically formaldehyde, other similar condensation productscan be made from other aldehydes, such as acetaldehyde, crotonaldehyde,acrolein, benzaldehyde, furfural, glyoxal and the like, and mixturesthereof. Exemplary commercially available amino crosslinking resinsinclude CYMEL™ 301, CYMEL 303, CYMEL 370, CYMEL 373, CYMEL 1131, CYMEL1125, CYMEL 5010 and MAPRENAL™ MF 980 (all available from CytecIndustries Inc.) and URAMEX™ BF 892 (available from DSM).

An optional catalyst may be employed to increase the rate of cure or theextent of crosslinking. Suitable catalysts include those known for usein crosslinking resole type phenolic resins or for use in theelectrophilic substitution of aromatic rings. Exemplary such catalystsinclude strong acids (e.g., dodecylbenzene sulphonic acid (DDBSA,available as CYCAT 600 from Cytec), methane sulfonic acid (MSA),p-toluene sulfonic acid (pTSA), dinonylnaphthalene disulfonic acid(DNNDSA), triflic acid, phosphoric acid, vinyl phosphonic acid-modifiedacrylic resins, and mixtures thereof. If used, a catalyst may forexample be present in an amount of at least 0.01 wt. % or, at least 0.1wt. % based on the weight of nonvolatile material. If used, a catalystis preferably present in an amount no greater than 3 wt. % or no greaterthan 1 wt. %, based on the total weight of nonvolatile material.

If desired, the disclosed coating compositions may optionally includeother additives that do not adversely affect the coating composition ora cured coating resulting therefrom. The optional additives arepreferably at least substantially free of mobile or bound BPA andaromatic glycidyl ether compounds (e.g., BADGE, BFDGE and epoxy novalaccompounds) and are more preferably completely free of such compounds.Suitable additives include, for example, those that improve theprocessability or manufacturability of the composition, enhancecomposition aesthetics, or improve a particular functional property orcharacteristic of the coating composition or the cured compositionresulting therefrom, such as adhesion to a substrate. Additives that maybe employed include carriers, additional polymers, emulsifiers,pigments, metal powders or pastes, fillers, anti-migration aids,antimicrobials, extenders, curing agents, lubricants, coalescents,wetting agents, biocides, plasticizers, crosslinking agents, antifoamingagents, colorants, waxes, antioxidants, anticorrosion agents, flowcontrol agents, thixotropic agents, dispersants, adhesion promoters, UVstabilizers, scavenger agents or combinations thereof. Each optionalingredient can be included in a sufficient amount to serve its intendedpurpose, but preferably not in such an amount to adversely affect thecoating composition or a cured coating resulting therefrom.

A variety of carriers may be employed in the disclosed coatingcompositions. Exemplary such carriers include carrier liquids such asorganic solvents, water, and mixtures thereof. Exemplary organicsolvents include aliphatic hydrocarbons (e.g. mineral spirits, kerosene,high flashpoint VM&P naptha, and the like); aromatic hydrocarbons (e.g.benzene, toluene, xylene, solvent naphtha 100, 150, 200 and the like);alcohols (e.g. ethanol. n-propanol, isopropanol, n-butanol, iso-butanoland the like); ketones (e.g. acetone, 2-butanone, cyclohexanone, methylaryl ketones, ethyl aryl ketones, methyl isoamyl ketones, and the like);esters (e.g. ethyl acetate, butyl acetate and the like); glycols (e.g.butyl glycol), glycol ethers (e.g. ethylene glycol monomethyl ether,ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,propylene glycol monomethyl ether, and the like); glycol esters (e.g.butyl glycol acetate, methoxypropyl acetate and the like); and mixturesthereof. Preferably, the liquid carrier(s) are selected to provide adispersion or solution of the disclosed polyester polymer for furtherformulation. In some embodiments the disclosed coating compositionincludes at least about 20, more preferably at least about 30, and evenmore preferably at least about 35 wt. % carrier, based on the totalweight of the coating composition. In some embodiments the disclosedcoating composition includes less than about 90, more preferably lessthan about 80, and even more preferably less than about 70 wt. %carrier, based on the total weight of the coating composition

In some embodiments, the disclosed coating composition is a water-basedvarnish. In some such embodiments, preferably at least about 50 wt. % ofthe liquid carrier system is water, more preferably about 60 wt. % iswater, and even more preferably about 75 wt. % is water. Some suchembodiments include at least about 10 wt. % of water, more preferably atleast about 20 wt. % of water, and even more preferably at least about40 wt. % or at least about 50 wt. % of water, based on the total weightof the coating composition.

The disclosed coating compositions may be prepared by conventionalmethods in various ways. For example, the coating compositions may beprepared by simply admixing the polyester polymer, crosslinker and anyother optional ingredients, in any desired order, with sufficientagitation. The resulting mixture may be admixed until all thecomposition ingredients are substantially homogeneously blended.Alternatively, the coating compositions may be prepared as a liquidsolution or dispersion by admixing an optional carrier liquid, thepolyester polymer, crosslinker, optional catalyst, and any otheroptional ingredients, in any desired order, with sufficient agitation.An additional amount of carrier liquid may be added to the coatingcompositions to adjust the amount of nonvolatile material in the coatingcomposition to a desired level.

The total amount of solids present in the disclosed coating compositionsmay vary depending upon a variety of factors including, for example, thedesired method of application. Presently preferred coating compositionsinclude at least about 10, more preferably at least about 20, and evenmore preferably at least about 30 wt. % solids, based on the totalweight of the coating composition. Preferably, the coating compositionsinclude less than about 80, more preferably less than about 70, and evenmore preferably less than about 65 wt. % solids, based on the totalweight of the coating composition.

In another embodiment, the invention provides a coating composition thatincludes the disclosed polyester polymer in combination with an optionalthermoplastic dispersion and crosslinker. Such coating compositions maybe suitable for various applications including food or beveragepackaging applications. While not intending to be bound by any theory,it is believed that some of the disclosed polyester polymers are capableof stabilizing certain thermoplastic materials such as, for example,polyvinyl chloride (“PVC”) to prevent or decrease degradation of thethermoplastic material or a cured coating resulting therefrom. Thus, itis within the scope of this invention to include an efficacious amountof the disclosed polyester polymer (e.g., for purposes of stabilizingthe thermoplastic dispersion) in an organosol or plastisol coatingcomposition. Organosols useful in the compositions of the invention,include, for example, vinyl organosols. A discussion of suitablematerials and preparation methods for such compositions may be found,for example, in U.S. Pat. No. 8,481,645 B2 (Payot et al.). Organosolcoating compositions may for example include at least about 10, at leastabout 15 or at least about 20 wt. % of the disclosed polyester polymer,based on the total nonvolatile weight of the coating composition.Organosol coating compositions may for example include less than about90, less than about 70 or less than about 60 wt. % polyester polymer,based on the total nonvolatile weight of the coating composition.Organosol coating compositions may also include at least about 10, atleast about 15 or at least about 20 wt. % thermoplastic material, basedon the total nonvolatile weight of the coating composition. Theorganosol coating compositions may also include less than about 80, lessthan about 70, or less than about 65 wt. % of thermoplastic material,based on the total nonvolatile weight of the coating composition.

Exemplary thermoplastic materials include halogenated polyolefins, suchas copolymers and homopolymers of vinyl chloride, vinylidenefluoride,polychloroprene, polychloroisoprene, polychlorobutylene, andcombinations thereof. PVC is a particularly preferred thermoplasticmaterial. The thermoplastic material may for example have an Mn of fromabout 40,000 to about 300,000; from about 75,000 to about 200,000; orfrom about 100,000 to about 150,000. In applications involving packagingcoatings, dispersion grade thermoplastic particles are preferred, wherethe particles range in size from greater than 0 to about 5 microns,based on volume-average median particle diameter. Other sizes mayhowever be used, such as non-dispersion grade thermoplastic particlesthat range in size from about 5 to about 100 microns, based onvolume-average median particle diameter.

The thermoplastic material is preferably dispersed in a liquid carrierto form a thermoplastic dispersion. Examples of suitable liquid carriersinclude an organic solvent, a plasticizer, or mixtures thereof. Suitableorganic solvents may include polar solvents such as ketones (e.g., MIBKand DIBK), glycol ethers, alcohols, aliphatic hydrocarbons, aromatichydrocarbons, or mixtures thereof. In some embodiments, it may beadvantageous to choose a solvent that has an affinity to thethermoplastic material or one that can swell the thermoplastic particlesto facilitate storage stability of the liquid coating composition.Preferred liquid carriers exhibit sufficient volatility to substantiallyevaporate from the coating composition during the curing process.

Cured coatings of the invention preferably adhere well to metal (e.g.,steel, tin-free steel (TFS), tin plate, electrolytic tin plate (ETP),aluminum, etc.) and provide high levels of resistance to corrosion ordegradation that may be caused by prolonged exposure to products such asfood or beverage products. The coatings may be applied to any suitablesurface, including inside surfaces of containers, outside surfaces ofcontainers, container ends, and combinations thereof.

The disclosed coating composition can be applied to a substrate inliquid form or in solid form using any suitable procedure such as spraycoating, roll coating, coil coating, curtain coating, immersion coating,meniscus coating, kiss coating, blade coating, knife coating, dipcoating, slot coating, slide coating, powder coating and otherpremetered or otherwise controllable coating techniques. In oneembodiment where the coating is used to coat metal sheets or coils, thecoating can be applied by roll coating.

The coating composition can be applied on a substrate prior to, during(for example, by spraying the coating composition into apartially-formed container) or after forming the substrate into anarticle. In some embodiments, at least a portion of a planar substrateis coated with one or more layers of the disclosed coating composition,which is then cured before the substrate is formed into an article.

After applying the coating composition onto a substrate, the compositioncan be cured using a variety of processes, including, for example, ovenbaking by either conventional or convectional methods. The curingprocess may be performed in either discrete or combined steps. Forexample, the coated substrate can be dried at ambient temperature toleave the coating composition in a largely uncrosslinked state. Thecoated substrate can then be heated to fully cure the coatingcomposition. In certain instances, the coating composition can be driedand cured in one step. In preferred embodiments, the disclosed coatingcomposition is a heat-curable coating composition.

The curing process may be performed at any suitable temperature,including, for example, temperatures in the range of about 180° C. toabout 250° C. If the substrate to be coated is a metal coil, curing ofthe applied coating composition may be conducted, for example, bysubjecting the coated metal to a temperature of about 230° C. to about250° C. for about 15 to 30 seconds. If the substrate to be coated ismetal sheeting (e.g., such as used to make three-piece food cans),curing of the applied coating composition may be conducted, for example,by subjecting the coated metal to a temperature of about 190° C. toabout 210° C. for about 8 to about 12 minutes.

The disclosed coating compositions may be useful in a variety of coatingapplications. The coating compositions are particularly useful asadherent coatings on interior or exterior surfaces of metal containers.Examples of such articles include closures (including for exampleinternal surfaces of twist off caps for food and beverage containers);internal crowns; two- and three-piece cans (including for example foodand beverage containers); shallow drawn cans; deep drawn cans (includingfor example multi-stage draw and redraw food cans); can ends (includingfor example easy open food or beverage can ends); monobloc aerosolcontainers; and general industrial containers, cans, and can ends.

Preferred coating compositions are particularly suited for use oninterior or exterior surfaces of metal food or beverage containers,including food-contact surfaces. Preferably, the cured coatings areretortable when employed in food and beverage container applications.Preferred cured coatings are capable of withstanding elevatedtemperature conditions frequently associated with retort processes orother food or beverage preservation or sterilization processes.Particularly preferred cured coatings exhibit enhanced resistance tosuch conditions while in contact with food or beverage products thatexhibit one or more aggressive (or corrosive) chemical properties undersuch conditions. Examples of such aggressive food or beverage productsmay include meat-based products, milk-based products, acidic fruit-basedproducts, energy drinks, and acidic or acidified products.

The disclosed coating composition is particularly suitable for use as acoating on the food-contact surface of the sidewall of a three-piecefood can. The coating composition is typically applied to a metal sheetwhich is then typically cured prior to fabricating the coated sheet intothe sidewall of a three-piece food can.

Test Methods

The disclosed coating compositions may be evaluated using a variety oftest methods, including:

A. Solvent Resistance Test

The extent of “cure” or crosslinking of a coating is measured as aresistance to solvents, such as methyl ethyl ketone (MEK) or isopropylalcohol (IPA). This test is performed as described in ASTM D 5402-93.The number of double rubs (viz., one back-and-forth motion) is reported.Preferably, the MEK solvent resistance is at least 30 double rubs.

B. Adhesion Test

Adhesion testing may be performed to assess whether the coatingcompositions adhere to the coated substrate. This test is performedaccording to ASTM D 3359—Test Method B, using SCOTCH™ 610 tape,available from 3M Company of Saint Paul, Minn. Adhesion is generallyrated on a scale of 0-10 where a rating of “10” indicates no adhesionfailure, a rating of “9” indicates 90% of the coating remains adhered, arating of “8” indicates 80% of the coating remains adhered, and so on. Acoating is considered herein to satisfy the Adhesion Test if it exhibitsan adhesion rating of at least 8.

C. Blush Resistance Test

Blush resistance measures the ability of a coating to resist attack byvarious solutions. Typically, blush is measured by the amount of waterabsorbed into a coated film. When the film absorbs water, it generallybecomes cloudy or looks white. Blush may be measured visually using ascale of 0-5 where a rating of “0” indicates no blush, a rating of “1”indicates slight whitening of the film, and a rating of “3” indicateswhitening of the film, and so on. Blush ratings of “2” or less aretypically desired for commercial packaging coatings and optimally “1” orless.

D1. Process or Retort Resistance Test

This is a measure of the coating integrity of a coated substrate afterexposure to heat and pressure with a liquid such as water. Retortperformance is not necessarily required for all food and beveragecoatings, but is desirable for some product types that are packed underretort conditions. The procedure is similar to a Sterilization orPasteurization Test. Testing is accomplished by subjecting the substrateto heat ranging from 105-130° C. and pressure ranging from 0.7 kg/cm² to1.05 kg/cm² for a period of 15 to 90 minutes. The coated substrate isthen tested for adhesion and blush as described above. In food orbeverage applications requiring retort performance, adhesion ratings of10 and blush ratings of at least 7 are typically desired forcommercially viable coatings.

D2. Retort Method

This test provides an indication of an ability of a coating to withstandconditions frequently associated with food or beverage preservation orsterilization. Coated ETP flat panels may be placed in a vessel andpartially immersed in a test substance. While totally immersed in thetest substance, the coated substrate samples are placed in an autoclaveand subjected to heat of 130° C. and pressure of 1 atmosphere aboveatmospheric pressure for a time period of 60 minutes. Just after retort,the coated substrate samples are tested for adhesion, blush resistance,or stain resistance.

E. Wedge Bend Test

This test provides an indication of a level of flexibility of a coatingand its extent of cure. Test wedges are formed from coated 12 cm long by5 cm wide rectangular metal test sheets. Test wedges are formed from thecoated sheets by folding (viz., bending) the sheets around a mandrel. Toaccomplish this, the mandrel is positioned on the coated sheets so thatit is oriented parallel to, and equidistant from, the 12 cm edges of thesheets. The resulting test wedges have a 6 mm wedge diameter and alength of 12 cm. To assess the wedge bend properties of the coatings,the test wedges are positioned lengthwise in a metal block of a wedgebend tester and a 2.4 kg weight is dropped onto the test wedges from aheight of 60 cm. The deformed test wedges are then immersed in a coppersulphate test solution (prepared by combining 20 parts of CuSO₄.5H₂O, 70parts of deionized water, and 10 parts of hydrochloric acid (36%)) forabout 2 minutes. The exposed metal is examined under a microscope andthe millimeters of coating failure along the deformation axis of thetest wedges is measured. The results may be expressed as a wedge bendpercentage using the following calculation:

100%×[(120 mm)˜(mm of failure)]/(120 mm).

A coating is considered to satisfy the Wedge Bend Test if it exhibits awedge bend percentage of 70% or more.

The invention is illustrated by the following examples. It is to beunderstood that the particular examples, materials, amounts, andprocedures are merely illustrative and that other embodiments may bemade as described. Unless otherwise indicated, all parts and percentagesare by weight.

EXAMPLES Example 1 Reaction of Tetramethyl Bisphenol F with EthyleneCarbonate

4,4′-Methylenebis(2,6-dimethylphenol) and a 10% molar excess of ethylenecarbonate were combined in a reaction vessel and heated to 100° C. 0.1Wt. % 1,5-Diazabicyclo[4.3.0]non-5-ene (DBN) based on the weight ofreactants was added to the vessel to catalyze the reaction. The reactionvessel was held at 150° C. for one hour and then at 180° C. until thecarbonate infrared absorption bands disappeared after about 4 hours. Theproduct, a diol of Formula III, contained 0.14 wt. % unreacted4,4′-Methylenebis(2,6-dimethylphenol) and 3.6 wt. % unreacted ethylenecarbonate.

Example 2 Reaction of Cardanol with Glycerine Carbonate

Cardanol and a 20% molar excess of glycerine carbonate were combined ina reaction vessel and heated to 120° C. 0.1 Wt. % DBN based on theweight of reactants was added to the vessel to catalyze the reaction.The reaction vessel was held at 180° C. for 4 to 5 hours until thereaction was complete as monitored by infrared spectroscopy and thecessation of CO₂ bubble formation. The product, a diol of Formula IX,contained 1.23 wt. % unreacted cardanol and less than 0.02 wt. %unreacted glycerine carbonate.

Example 3 Reaction of Tetramethyl Bisphenol F with Propylene Carbonate

Using the method of Example 1, 4,4′-Methylenebis(2,6-dimethylphenol) anda 10% molar excess of propylene carbonate were combined in a reactionvessel and heated to 120° C. 0.1 Wt. % DBN based on the weight ofreactants was added to the vessel to catalyze the reaction. The reactionvessel was held at 180° C. for 5 hours until the reaction was completeas monitored by infrared spectroscopy and the cessation of CO₂ bubbleformation. The product, a diol of Formula III, contained 0.02 wt. %unreacted 4,4′-Methylenebis(2,6-dimethylphenol) and 4.2 wt. % unreactedpropylene carbonate.

Example 4 Reaction of (2,2′-Methylenebis(6-Tert-Butyl-4-Methylphenolwith Ethylene Carbonate

Using the method of Example 1, IONOL 46(2,2′-methylenebis(6-tert-butyl-4-methylphenol) and a 10% molar excessof ethylene carbonate were combined in a reaction vessel and heated to120° C. 0.1 wt. % DBN was added to the vessel to catalyze the reaction.The reaction vessel was held at 180° C. for 5 hours until the reactionwas complete as monitored by infrared spectroscopy and the cessation ofCO₂ bubble formation. The product was a diol of Formula III.

Example 5 Polyester Synthesis Using Formula III Diol

The Formula III diol prepared in Example 1 was used to make asolvent-borne polyester polymer containing segments of Formula XIIIshown below:

The reaction was performed by mixing 12.25 g neopentyl glycol, 2.52 gethylene glycol, 10.69 g cyclohexanedimethanol, 33.1 g of the Example 1diol, 35.66 g isophthalic acid, 12.76 g cyclohexane dicarboxylic acid,1.12 g maleic anhydride and 0.09 g organometallic catalyst in a reactionvessel equipped with an overhead stirrer, heating mantle, packed columnwith Raschig rings, distilling head and condenser. The reaction mixturewas heated to and maintained at 240° C. until an acid value of 20 wasobtained. Next, 2.66 g sebacic acid and 8.7 g xylene were added to thereaction vessel, the packed column and distilling head were replaced bya Dean-Stark trap, and the reaction mixture was heated to reflux untilan acid value of 5 was obtained. The reaction mixture was cooled anddiluted with 34.2 g butyl glycol to provide the finished polyestersolution.

Example 6 Polyester Synthesis Using Formula IX Diol

The Formula IX diol prepared in Example 2 was used to make asolvent-borne polyester polymer containing segments of Formula XIV shownbelow:

The reaction was performed by mixing 10.78 g neopentyl glycol, 2.21 gethylene glycol, 18.11 g cyclohexanedimethanol, 20.04 g of the Example 2diol, 36.44 g isophthalic acid, 12.42 g cyclohexane dicarboxylic acidand 0.09 g organometallic catalyst in a reaction vessel equipped with anoverhead stirrer, heating mantle, packed column with Raschig rings,distilling head and condenser. The reaction mixture was heated to andmaintained at 230° C. until an acid value of 20 was obtained. Next, 5.3g xylene was added to the reaction vessel, the packed column anddistilling head were replaced by a Dean-Stark trap, and the reactionmixture was heated to reflux until an acid value of 5 was obtained. Thereaction mixture was cooled and diluted with 37.6 g butyl glycol toprovide the finished polyester solution.

Example 7 Acrylated Polyester Synthesis Using Formula III Diol

The Formula III diol prepared in Example 1 was used to make awater-based acrylated polyester by heating at 130° C. 70 g (dry basis)of the Example 5 polyester, 23.94 g butyl glycol and 1.609 g Xylene andadding over the course of 2 hours a 130° C. heated monomer feedcontaining 1.2 parts 2,2′-Azodi(2-methylbutyronitrile) (AMBN) initiator,14 g ethyl acrylate, 5.89 g styrene, 4.24 g acrylic acid and 5.89 ghydroxyethyl acrylate. One hour after the end of the heated monomerfeed, the reaction mixture was spiked with 0.16 g tert-butylperoxybenzoate initiator (TBPB). The reaction mixture was maintained at130° C. for about two hours until the measured nonvolatile content (NVC)reached 70%. A 0.5 g portion of the reaction product was heated at 180°C. for 1 hour and determined to have an acid value of 32.5 and a 70.1NVC. The remaining reaction product was cooled to 97° C. and the acidcontent fully neutralized by adding a 50% by weight solution ofdimethylethanolamine (DMEA) in water over a 10 minute period. Theresulting product was held at 97° C. for a 30 minute period, the dilutedwith hot water added over the course of one hour until the NVC reached30%. The final product characteristics were: NVC=29.5%, viscosity 43seconds at 25° C. using a No. 4 Afnor viscosity flow cup, and pH=8.5.

Example 8 Acrylated Polyester Synthesis Using Formula IX Diol

The Formula IX diol prepared in Example 2 was used to make a water-basedacrylated polyester by heating at 130° C. 70 parts (dry basis) of theExample 6 polyester, 26.3 g butyl glycol and 3.7 g xylene and addingover two hours at 130° C. a heated monomer feed containing a mixture of1.2 parts AMBN, 12.42 parts ethyl acrylate, 5.89 g styrene, 5.79 gacrylic acid and 5.89 g hydroxyethyl acrylate to provide an acrylatedpolyester containing 70% NVC. One hour after addition of the heatedmonomer feed, the reaction mixture was spiked with 0.16 g TBPB, thenheld for two hours at 130° C. and spiked again with 0.16 g TBPB. Thereaction mixture was maintained at 130° C. for about one hour until theNVC reached 70%. A 1 g portion of the reaction product was heated at180° C. for 30 minutes and determined to have an acid value of 43.5 anda 70% NVC. The remaining reaction product was cooled to 97° C. and theacid content fully neutralized by adding a 50% by weight solution ofDMEA in water over a 10 minute period. The resulting product was held at97° C. for a 30 minute period, the diluted with hot water added over thecourse of one hour until the NVC reached 28%. The final productcharacteristics were: NVC=27.3%, viscosity 136 seconds at 25° C. using aNo. 4 Afnor viscosity flow cup, and pH=8.8.

Example 9 Solvent-Based Coating Formulations

To the polyester solutions of Examples 5 and 6 were added with stirringa resole-type phenolic resin and an acidic catalyst. The solutionviscosities were adjusted using a xylene-butanol solvent blend. Aftercomplete homogenization the coating compositions were allowed to standfor 12 hours at room temperature, then applied at a 6-8 g/m² dry filmweight on tinplate panels bearing a 2.8 g/m² tin film weight coating andcured for 10 minutes at 200° C. (time at peak metal temperature). Aftercooling, some of the coated panels were drawn in order to produce a 4cornered asymmetrical box or regular ends. The boxes, ends and flatpanels were then retorted for one hour at 130° C. in water, water+3%acetic acid or water+1% sodium chloride. The appearance, adhesion andflexibility of the coated panels was evaluated using a 0-5 scale bycomparing the coated panels to a reference series of standard coatedpanels. The coating recipes are set out below in Table 1 and theevaluation results are set out below in Table 2:

TABLE 1 Coating Recipes Ingredient Coating 1 Coating 2 Example 5Polyester (55% NVC) 59 Example 6 Polyester (70% NVC) 47 Resole TypePhenolic resin (60% 12 12 NVC in Butanol) Sulfonic acid catalyst (5% in2 DOWANOL ™ DPM) Phosphoric acid catalyst (10% in 0.5 DOWANOL DPM)Xylene 16 29 Butanol 4 4

TABLE 2 Evaluation (scale 0-5, 5 = the best) Test Panel Coating 1Coating 2 4c box retorted 4 Loss of adhesion on 3 corners in 3% aceticacid (slight blush and bubbling) 4c box retorted 5 Loss of adhesion on 3corners in water (no blush, no bubbling) 4c box retorted 5 Loss ofadhesion on 3 corners in 1% salt water (no blush, no bubbling) Flatpanels 4 4 retorted in 3% (slight blush, (slight blush, acetic acid veryslight bubbling) no blistering Flat panels 4.5 5 retorted in 1% (veryslight blush, (no blush, excellent adhesion, salt water no bubbling) noblistering) Flat panels 5 5 retorted in water (no blush, (no blush, nobubbling) excellent adhesion)

Example 10 Water-Based Coating Formulations

The polyester of Example 8 was employed at two different solids levelsand stirred together with two different resole-type phenolic resins, anamine-neutralized sulfonic acid catalyst, and a vinyl phosphonic acidacrylic resin that had been neutralized with amine in order to make theresin water soluble. The acrylic resin serves as both an adhesionpromoter and crosslinking catalyst. The coating composition viscositieswere adjusted with deionized water to a target of about 60 seconds at25° C. using a No. 4 Afnor viscosity flow cup. After completehomogenization the coating compositions were allowed to stand for 12hours at room temperature, then applied at a 6-8 g/m² dry film weight ontinplate panels like those used in Example 9 and cured for 4 or 10minutes at 200° C. (total oven time). After cooling the coated panelswere drawn to produce regular ends and retorted and evaluated as inExample 9. The coating recipes are set out below in Table 3 and theevaluation results are set out below in Table 4:

TABLE 3 Coating Recipes Ingredient Coating 3 Coating 4 Example 8Polyester (30% NVC) 69 Example 8 Polyester (27% NVC) 50 Resole TypePhenolic resin 1 3 Resole Type Phenolic resin 2 5 Amine-neutralizedsulfonic acid 5 2 catalyst Amine-neutralized vinyl phosphonic 4 4.8 acidacrylic resin Water To adjust To adjust viscosity viscosity

TABLE 4 Evaluation (scale 0-5, 5 = the best) Coating 3 Coating 3 Coating4 Coating 4 4 min 10 min 4 min 10 min Test Panel 200° C. 200° C. 200° C.200° C. Ends retorted in 5 5 water (no blush, (no blush, excellentexcellent adhesion) adhesion) Ends retorted in 4 4.5 4.5 5 3% aceticacid (slight blush, (slight blush, (slight blush, (no blush, excellentexcellent excellent excellent adhesion) adhesion) adhesion) adhesion)Ends retorted in 5 5 1% salt water (no blush, (no blush, excellentexcellent adhesion) adhesion)

Having thus described preferred embodiments of the present invention,those of skill in the art will readily appreciate that the teachingsfound herein may be applied to yet other embodiments within the scope ofthe claims hereto attached. The complete disclosure of all patents,patent documents, and publications are incorporated herein by referenceas if individually incorporated.

1-36. (canceled)
 37. A coating composition comprising: (a) a polyesterpolymer derived by esterifying an aryloxy ether polyol derived fromreaction between: (i) a polyhydric phenol or a polyphenol and anon-hydroxyl functional cyclic carbonate, or (ii) a monophenol and ahydroxyl functional cyclic carbonate; (b) a crosslinker and (c) anoptional catalyst.
 38. A coating composition according to claim 37,wherein the aryloxy ether polyol is a diol having the formula:

wherein: each R¹ may be the same or different and independently is amonovalent atom or a monovalent organic group and may containheteroatoms; R² is hydrogen or an organic group; x is 0 to about 2; andy is 1 to about
 10. 39. A coating composition according to claim 37,wherein the aryloxy ether polyol is a diol derived from reaction betweena polyhydric phenol or a polyphenol and a non-hydroxyl functional cycliccarbonate, and the polyhydric phenol has the formula:

wherein: each R¹ may be the same or different and independently is amonovalent atom or a monovalent organic group and may containheteroatoms, or the polyhydric phenol has the formula:

wherein: H denotes a hydrogen atom, if present; A, if present, is adivalent organic group; each R³, if present, is independently an atom orgroup having at atomic weight of at least 15 Daltons; m is 0 or 1, withthe proviso that if m is 0, the phenylene rings depicted in Formula IAcan optionally join with each other to form a fused ring system, inwhich case v is 3 and w is 0 to 3; v is 4; and w is 0 to
 4. 40. Acoating composition according to claim 37, wherein the aryloxy etherpolyol is a diol derived from reaction between a polyhydric phenol or apolyphenol and a non-hydroxyl functional cyclic carbonate having theformula:

wherein R² is hydrogen or an alkyl group.
 41. A coating compositionaccording to claim 37, wherein the aryloxy ether polyol is derived froma polyhydric phenol or a polyphenol comprising catechol, a substitutedcatechol, hydroquinone, a substituted hydroquinone, resorcinol, asubstituted resorcinol, 4,4′, methylenebis(2,6-dimethylphenol),2,2′-methylenebis(6-tert-butyl-4-methylphenol),4,4′-methylenebis(2,6-di-tert-butylphenol),4,4′-butylidenebis[2-tert-butyl-5-methylphenol], spirobiindanebisphenol, bis-(hydroxy phenyl)-N-phenyl isoindolinone or mixturethereof.
 42. A coating composition according to claim 37, wherein thearyloxy ether polyol is derived from reaction between a monophenol and ahydroxyl functional cyclic carbonate, the monophenol has the formula:

wherein each R⁴ may be the same or different and independently is amonovalent atom or a monovalent organic group and may containheteroatoms, and the hydroxyl functional cyclic carbonate has theformula:

wherein R⁵ is an alkyl group.
 43. A coating composition according toclaim 37, wherein the aryloxy ether polyol is derived from a polyhydricphenol or polyphenol having low estrogenicity.
 44. A coating compositionaccording to claim 37, wherein the cyclic carbonate comprises ethylenecarbonate, propylene carbonate, butylene carbonate or glycerinecarbonate.
 45. A coating composition according to claim 37, wherein thepolyester polymer is derived from: a) maleic acid, fumaric acid,succinic acid, adipic acid, phthalic acid, tetrahydrophthalic acid,methyltetrahydrophthalic acid, hexahydrophthalic acid,methylhexahydrophthalic acid, endomethylenetetrahydrophthalic acid,azelaic acid, sebacic acid, tetrahydrophthalic acid, isophthalic acid,terephthalic acid, naphthalene dicarboxylic acid, cyclohexanedicarboxylic acid, glutaric acid, a dimer fatty acid, or an anhydride,alkyl ester or mixture thereof, and b) ethylene glycol, propyleneglycol, 1,3-propanediol, 2-methyl-1,3-propanediol,2-butyl-2-ethyl-1,3-propanediol, glycerol, diethylene glycol,dipropylene glycol, triethylene glycol, trimethylolpropane,trimethylolethane, tripropylene glycol, neopentyl glycol,pentaerythritol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol,1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol,2-methyl-2,4-pentanediol, 4-methyl-2,4-pentanediol, 2,2,4-trimethyl1-3-pentanediol, 1,5-pentanediol, 1,6-hexanediol,2,2-dimethyl,1,3-hexanediol, cyclohexanedimethanol, a polyethylene orpolypropylene glycol, isopropylidene bis (p-phenylene-oxypropanol-2),hydroxypivalyl hydroxypivalate or mixture thereof.
 46. A coatingcomposition according to claim 37, wherein the polyester polymer has anacid number less than about 20, a number average molecular weight (Mn)of at least about 1,000 and less than about 20,000, and a Tg of at least0° C. and less than 100° C.
 47. A coating composition according to claim37, wherein the polyester polymer is water dispersiblc or water soluble.48. A coating composition according to claim 37, further comprising acarrier liquid comprising an organic solvent, water, or mixture thereof.49. A coating composition according to claim 37, wherein the polyesterpolymer is substantially free of mobile bisphenol A (BPA) and aromaticglycidyl ether compounds.
 50. A coating composition according to claim37, wherein the crosslinker comprises a phenolic crosslinker, aminocrosslinker, blocked isocyanate crosslinker, material containing oxiranegroups, or combination thereof.
 51. A coating composition according toclaim 37, wherein the coating composition comprises about 10 to about 90wt. % polyester polymer, about 0.1 to about 15 wt. % crosslinker, 0 toabout 3 wt. % catalyst and an optional carrier.
 52. An article coated onat least one surface with a coating composition according to claim 37.53. An article according to claim 52, wherein the surface comprises afood-contact surface.
 54. An article according to claim 53, wherein thearticle comprises a food or beverage can.
 55. A method for producing acoated article, comprising: providing a coating composition according toclaim 37; and applying the coating composition on a metal substrateprior to, during, or after forming the substrate into an article such asfood or beverage can or other container or a portion thereof.
 56. Amethod for making a coating composition, which method comprises: (a)preparing an aryloxy ether polyol by reacting (i) a polyhydric phenol ora polyphenol and a non-hydroxyl functional cyclic carbonate, or (ii) amonophenol and a hydroxyl functional cyclic carbonate; and (b) preparinga polyester polymer by esterifying the aryloxy ether polyol.